Nitride semiconductor laser chip
View Patent ↗A nitride semiconductor laser chip is provided that offers sufficient reliability even at high output. The nitride semiconductor laser chip has a nitride semiconductor layer formed on a substrate, a resonator facet formed on the nitride semiconductor layer, and a coating film formed on the resonator facet and containing Ar. The coating film has, in a region contiguous with the resonator facet and in the vicinity thereof, a low-Ar region with a low Ar content and, on the side of this low-Ar region opposite from the resonator facet, a high-Ar region with a higher Ar content than the low-Ar region.
1. A nitride semiconductor laser chip comprising:
a nitride semiconductor layer formed on a substrate;
a resonator facet formed on the nitride semiconductor layer; and
a coating film formed on the resonator facet and containing a rare gas element,
the coating film including a first region and a second region,
the first region being in contact with the resonator facet and disposed between the resonator facet and the second region, and
a percentage by number of atoms of the rare gas element in the first region being lower than a percentage by number of atoms of the rare gas element in the second region.
2. The nitride semiconductor laser chip according to claim 1 , wherein the first and second regions are formed of mutually different materials.
3. The nitride semiconductor laser chip according to claim 1 , wherein the first and second regions are formed of a same material.
4. The nitride semiconductor laser chip according to claim 1 , wherein the first region of the coating film includes an aluminum nitride film or an aluminum oxynitride film.
5. The nitride semiconductor laser chip according to claim 1 , wherein the first region of the coating film includes an aluminum oxide film.
6. The nitride semiconductor laser chip according to claim 1 , wherein the second region of the coating film includes an aluminum oxide film, a silicon oxide film, or a silicon nitride film.
7. The nitride semiconductor laser chip according to claim 1 , wherein the first region has a thickness of 5 nm or more but 100 nm or less in a thickness direction of the coating film.
8. The nitride semiconductor laser chip according to claim 1 , wherein the second region has a greater thickness than the first region in a thickness direction of the coating film.
9. The nitride semiconductor laser chip according to claim 1 , wherein the rare gas element is argon, and a percentage by number of atoms of Ar in the first region is 3% or less by number of atoms.
10. The nitride semiconductor laser chip according to claim 9 , wherein the percentage by number of atoms of Ar in the first region is 1% or less by number of atoms.
11. The nitride semiconductor laser chip according to claim 1 , wherein the resonator facet comprises a light-emission-side resonator facet and a light-reflection-side resonator facet, and the coating film comprises a coating film formed on the light-emission-side resonator facet and a coating film formed on the light-reflection-side resonator facet.
12. The nitride semiconductor laser chip according to claim 1 , wherein the first region in the coating film is crystallized.
13. The nitride semiconductor laser chip according to claim 1 , wherein the second region in the coating film includes at least a region in an amorphous state.
14. The nitride semiconductor laser chip according to claim 1 , wherein the percentage by number of atoms of the rare gas element in the first region is less than 3% by number of atoms.